[GUEST]

Hi,
Can some one help with calculation methodology to workout the rating of the Battery for UPS.
To be more specific, I was looking for a 2 KVA UPS to cater 6 PCs for a back-up tme period of 1 hr. I found each & every manufacturer recommending different rating of Battery AH & quantities. Please help me with the calculation to make right judgment.

Topic

[Hamid]

Two methods are used to size stationary batteries, constant current and constant power. Constant current is used for applications such as generating stations, substations, and industrial control. Constant-power sizing is used almost exclusively for UPS system applications. Unlike constant-current loads, the current of a constant-power load (e.g., an inverter or dc motor) increases as the battery terminal voltage decreases during a discharge, so that P =E x I remains constant. Load profiles are not normally drawn for constant-power sizing since the load, once applied, remains the same throughout the battery discharge. A more detailed discussion of constant-power sizing is included in IEEE Standard 1184. Electric utility and industrial control-voltage windows generally use the standard cell end voltage but are sometimes limited by the minimum system-voltage limit. UPS applications can offer the largest voltage window, since the inverter input can be designed to accept a wide range of voltage without affecting the inverter

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